Ghostwatch is another one of my favourite hoaxes. I watched it about 4 or 5 years ago on the Scream channel and immediately went into researching why the show has never been played in the UK since it originally aired.
Basically it's a faux documentary presented as a live BBC broadcast, following a little girl who claims her house is haunted. Since there were a lot of television shows about hauntings, and paranormal research at the time, and the use of real tv personalities, I can see why people would have believed this hoax at the time.
Here's a
link to a blog with some info that was collected for a documentary, about Ghostwatch (that may, or may not ever happen).